Telephone-exchange system



May 26, 1925.

f7./ fiyi 596. fig] H 2 F/qJ 594 May 26, 1925.

- 1,539,380 S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1922 8 Sheets-Sheet 2 I fiver/fonsamue/ 5. VI/ifiams May 26, 1925.

. 1,539,380 s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1922 8 Sheets$heet 5 hi/enlbn Sdmue/ B. MOW/arms May 26, 1925.

' 1,539,380 S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1922 8 Sheets-Sheet 4 //7vnf0/ Samue/ 5. WY/iams s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM 8 Sheets-Sheet 5 lm/enfon' Samue/ VV/W/ams Filed Dec. 5, 192g May 26, 1925.

1,539,380 S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Dec. 5, 1922 8 Sheets-Sh 6 hven/bn' Samue/ 5. VV/Wdams.

1,539,380 S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1922 8 Sheets-$heet 7 Samue/ 5. VV////'4ms Patented May 26, 1925, w

. $AMUEL n..w;rLnrn yrs, ;or snoo gpirn nnw you}; .ASSIGNOR ro wns rsaN-nnsormo conmnmanconronaprnn r nnw yoan n. y.,.a cosrona'rron ornnwyon g.

'rnLErHoNE-ExoHaneE SYSTEM.

ApplicationfiledDecember 5,;1822. Serial No. 604 975. 7 V

system 011" the character wliereinjtalking conmotions are established partly through the agency of manually operated equipment and partly throughthe medium of machine switching apparatus.

A featurepf the invention relatesto an arrangement 7 wherein a sw tch controlling i'egister sender is connected to any one of a number of c rcuits;outgolng'troln an operaof making connection with such circuit.

Another feature relates to the provision of an arrangement wherein connectingcircuits outgoinglrom a plurality of operators positions appearin a single coordinateswitch,

which serves to extend-said circuits over the trunks of a ,group outgoing from such switch.

A further feature relates;to a register sender, arranged'for connection with; trunks outgoing froint-he operatorls position when she makes connection with such trunks,

adapted togtransmit a recordover'the trunk toa distant controlling mechanism by means of code impulses.

A still "further :t'eaturerelates to an improved overflow arrangementwhereby any operator may appropriate"for use the connecting circuits at other operators positious.

Other and turther features contemplated in this invention will become apparent from the detailed description giyen hereinafter and also from the appended claims.

Referring. to the draw ng-Figsql to 7, 1n-

elusive, when arranged inthel' order, shown in Fig. "9, clisciosea telepl'roneexchange systern incorporating tlialeatures oi the" invention. 1 f Fig. 1 shows asubscr i-bers line terminating before operator in. al nanual oflice and .set 1 consisting I of -ten non-locking keys. the right of this figure is-shown thefirst of series of four relay registers. -.F ig..r l .shows'the remaining three relayregisters of :the series. i

also one of the operators cord circuits. Be-

low the horizontal'broken ;line ;t-hi s ligure also illustrates two connecting circuits outgoing irom the part cular operators p$1 blOlIilhWlllOll' the cord circuit ShOWlrislocated. Above thedrorizontal broken line. is

1 shown a connecting circuit appearing at an- ,otherwoperatofls position.

:Fi s. 2, 3 and A illustrate ,a register sender rd evice associated .with: the operators position illustrated in full in Fig. l. .F i 2 shows certain controlling relays and circuits. Fig. 3 at the left shows the operatorsliQY Fig. 5 shows one of anumber of coordinate meeting, cir-cuitsleading i from, a plurality of I operators positions to a group of trunks outgoinglto a distant mechan cal office. tors positionresponsive to tlie operators act Fig; 6 illustrates Ea distant mechanical office in which the automatic switches, diagrammatically shown, serve 'to extend the incomingtrunkto a, called subscribers line.

Also, this figureshows in thespace at-the left and above the broken line, senderse- ,lecting switch and certain controlling relays and elements associated-with the first olithe group selecting switches. In the spacebe- 1 low and to, the right of the broken line there 11S shown, the receiving portion .Of the register COHiEIOlllllg'11166112111511].

l ig.,7.s'h0Ws:the relaysecond registers of the register controlling mechanism.

irepresented bytwo of a number of operators .positionsSOO and 610. i Calls are recelvedat the operators positions in anv we-llknoewn inannermid are answered bythe operators through the use of cord circuits,- such as the cord .801 located ,at position SOD-and .cordf837 located at position Ell'O.

Outgoing from the operators .positionSOO there are a number ofgiioups of. connecting -circi'ut s, one group. .tor each distant mechanical ofiire to which this particular operator inayhave access. Circuits llland 8O3 are "two of a group over which the operator at position 800 mayes'tah'lish connections to the distant mechanical otiice 825. Similarly circuits 80st and 805 are two of a second group over which the operator may establish connections with the distant mechanical oflice 835. Circuits 802, 803, 80 1 and 805 appear at the position in the regular jacks 806, 807, 808 and 809 and also in the overflow jacks, respectively, 811, 812, 813 and 814. Circuits 802 and 803 extend from the operators position and appear in the vertical row of the coordinate switch 820.

' Switch 820 serves to extend connections to the mechanical otlice 825. Consequently there appear in this switch the connecting circuits leading from each of a plurality of the operators positions. Circuits 802 and 803 appearing in this switch come from the operators position 800. Circuits 838 and 839 are two of a group appearing before the second operatofsposition 810 and which also lead to an incoming vertical row of the coordinate switch 820. Similarly, other groups of circuitsat other operators positions may appear in the switch 820 for connection with the distant mechanical office 825. Outgoing from the switch 820 is a group of inter-otlice trunks of suitable size, three ofwhich, trunks 821, 822 and 823, are shown. In the manner to be explained hereinafter, the connecting circuits leading from the operators position to the switch 820 are connected to the outgoing trunks through the medium of linlcs 82t, 826, 827 and 828.

Also associated with the operators position 800 is a register sender controlling device 815. The sender 815 is common to all circuits ot all groups outgoing From the operators position and may be associated with any one of said circuits in response to the act by the operator of inserting one of her plugs in the regular jack of such mitgoing circuit. llhe operator by means of the ltey set sets up a numerical record on the sender which later transmits code im- *ators position 800 appear in the switch 830 and are extended thereby to the distant ofiice 835. Similarly, corresponding groups of circuits leading from other operators positions appear in the switch 830 for a similar purpose. 7

The operators position 810 is also equipped with a sender 829 which corresponds to thesender 815,

Should the op rat r at any p siti n, 2.8,

the position 810 and connects it instead to the sender 815. In thisway any operator may use the connecting circuits outgoing from another position inorder to route calls to a given distantmechanical office when all of the corresponding circuits at her own position are in use.

The coordinate switches illustrated in Fig. 8 diagrammatically, and shown in detail as the switch 500 in Fig. 5, may be of the same general character as the switch described in detail in the British patent No. 183,438, issued to Western Electric Company, Limited, accepted September 6,1923.

A specific description will now be given explaining the manner in which the system operates whena connection is extended from the subscribers line 100, which is assumed to terminate in the operators position 105 of the manual ofiice illustrated in Fig. 1, to the subscribers line 633 terminating in the distant mechanical ofiice. When the subscriber of line, 100 initiates a call, the operator responds in the usual manner by ii'iserting theplug 1010f an idle cord circuit 101 in the jack 103. The operator converscs with the calling subscriber in the usual inannerand obtains fromhiin. orally the name of the desired oflice and the number of the called subscribei"s line therein. Having received this information and know ing that the call is one for the particular mechanical ottice illustrated in Fig. 6, the operator seizes the plug 100 andnotes it there is an idle connecting circuit of the particular group over which the connection may ,be routed to the required mechanical oflice.

Finding that the connecting circuit 108 of the proper group is idle, the operator inserts plug 106 into the regular jack 111 of said circuit.

1 The insertion of the plug 106 into jack 11.1 completes a circuit from battery through the winding of relay 107, sleeve of plug 106, sleeve ofjack lll, winding of relay 121 to ground. Relay 121 operates and closes a circuit from battery through the winding of relay 516, conductor 132, outer right contact of relay 119, left back contact of relay 120, left contact of relay 121, lower back contact of relay 122, conductor 137, winding of relay 202, contact of relay 203 to ground. Relays 516 and 202 operate in this circuit.

Relay'516serves to initiate the operation of the coordinate switch 50mmth e p,u-r-- pose of extending the connecting circuit 108 through anidle'linlc' 505, 506, etc, to'anoutgoing trunk" 509,. 510, vctci,leading to' the distant mechanica-lofiice. The connecting circuit108 is seento appear inthe'ver ticalro-w of contacts 501 together withthc other connecting circuit'109leading from the same op'eratofis position. A second vertical row of contacts 502"is illustrated in which connecting circuits. 511' and 524 appear incoming from the same or anotheroperators position. Only'two trunks 509'and 5-10 occupying respectively the complete vertical rows-50etand .503 are shown, although there maybe as many as necessary;

When-the relay 516op'erates, it closes a circuit from battery tliroughtlie winding o'f'the verticalopjeratingmagnet 51.8 individuallto the row 501, conductor inner right contact of relay 516 to ground at the left contact ofone 0r-m0re ofthe horizontal operating magnets 512, 513, etc. The magnet 51S prepares-thecontacts in the vertical-row 501 and also establishes a circuit from ground through" its inner rightcontact, conductor 526, innermost left back contact of vertical inagnet 520, inner left front contactof relay 527 (assumingcthe trunk 510 to be busy), conducton528, outer left'contact of relay 523 (assuming the trunk 509 to be idle), winding of Vertical 0perating magnet 521 'to battery, Magnet 521 rotatestne associated rodand prepares the contacts in the-row 50 1. Magnet-521 completes a circuit from ground thi ough its middle contact, winding ot slow-to-rele ase relay lo battery. Relay 523" operates innncdiately and' closes a circuit from ground through its right contact, inner lett hack contact o't'slow-to-operate relay 522, winding of relay tohattery. Relay522 being slow to energize does not attract its arnuitures for an appreciable interval oil time after the closure ot'its circuit. Relay 523 in o 'ieratingopens the original encrgiz'ing, circuit of magnet-= ti'agnet 521, however, remains energized 'in a substitute circuit traceable as follows: battery, through the winding of said magnet, outer left back contact of rela -y innermost -l'ront contact of magnet 521, conductor 523, thence to= groijind atthe inner rightconact of 'ma gnet518. This holdingcircuit oit magnet 521 is maintained during the inter-val that relay 52-2 remains deenergized, which is sufiicient to-allow the operation of one of the. horizontal link magnets 5.12, 513 to establish the connectionthroughthe switch 50(1- Immediately that magnet 521 I operates and before relay;522 has timeto energize, a circuit is: closed from ground through the outermost leftcontact of inagnet 521, conductor 528, leai'tcontact ofmagnet'5l8, conductor 529, outer right back Contact of relay 517, outer right front conta'ctzof relay 516, normal contact" and winding'o'f horizontal link magnet to battery, assuniing the'li nk tobe idle at this time. Magnet: 5l2 rotates the associated bar and establishes connection ti-om the circuit 103 through the link 505 to the idle trunk50t iilagnet 512 in operating-extends the start wire through its outer right contact to the winding of the next link magnet 513. lVhen magnet 512 operates it closes a tern l '.i" Circuit'ior itself as follows: battery, through the winding and inner right front contact oi said magnet, sleeve conductor 530" of link 505, contacts of switclr500 in the row 5041, conductor 531, inner'leftback contact of relay 522, right contact of relay 523 to ground. The operation o t-theswitch 500 also establishes a circuit from batt ry througli'the winding of relay 120, sleeve conductor 131, through contacts of'tlie switch 500 by way ofliiik 505, thence over conductor 531 toground at: theu'ight contact otrelay' Relay 1.20 operates and looks through its Winding andu'ight contact to groundat the right contact at relay 121.

After'the necessary interyal has elapsed following the closure of the circuit of re lay 522, said" relay attracts its armatures and in so doing opens the holding circuit oi? the vertical n'iagnet 521. Magnet 521 restores theassociat'ed rod toits normal position and. also opens the circuit ot'ielay 523. lielay 523,however, remainsenergizeil in a circuit from battery through its winding. inner leftitront contactoi relay conductor 531 thence 'as tracedthrough contacts ol 'tho switch 500,'o\ 'er conductor 131. right. contact of relay 120 to ground at the right contact of 'relay121.

Relay in"operating, also opens the temporary holding circuit of the horizontal niagnet'512. li la-gnet 512, however, is held energized in acircuit from battery through its winding and inner right con-- tact; contacts oi the switch 500 in row 501, sleeve conductor 131m ground at the right contact otfrelay 121. 'Themaintained operation of relay'523 extends" the starter wire 538 through the inner left back contact of? magnet 521and the inner left front contact of relay to the next trunk.

.R-elay 522, in operating, opens its original. energizing circuit but this relay is; maintained energized in a circuit from battery through its winding, thence over conductor 531, through contacts 01" the switch 500 as traced. to groundfat the right contact oi relay 121?.

When relay'12O attracts its armatures it opens the circuittraced tor-relay 516. Relay 516 in releasing opens the'cir'cuit of the vertical magnet 518. Magnet 51S restores the associated rod and the connection is now held by the sole energization of the horizontal magnet 512. Relay 516 in releasing extends the starter wire 529 through to the corresponding relay at the next group of horizontal link circuits.

When relay 120 first operates it opens, as explained, the holding circuit of relay 516. Relay 516, however, being slow-to-release maintains its armatures attracted for a definite interval thereafter. lVhile relay 516 is remaining operated after the energization of relay 120, a circuit is closed from battery through the winding of relay 119, conductor 133, left contact of relay 516, conductor 134, left front contact of relay, 120, left contact of relay 121, lower back contact of relay 122, conductor 137, winding of relay 202 to ground at the contact of relay 203. Relay 119 operates and immediately locks through its inner right contact to ground over the circuit just traced. Relay 119, at its left contacts, opens the tip and ring conductors of the talking circuit 108 and connects said circuit to the register sender shown in Figs. 2, 3 and 4.

The operator on receiving the numerical designation of the called subscribers line proceeds at once to write the number on the single set of keys 300 at her position. To do this the operator depresses in succession four keys, each representing a digit in said number. Assuming the designation of the wanted line is 1246, the operator depresses first the No. 1 key 314, then the No. 2 key 315, then the No. 4 key 310 and lastly the No. 6 key 317.

The operation of key 314 establishes a circuit from ground through the right contacts of said key, conductor 318', thence in parallel through the winding of relay 319 and through the lower back contacts of relays 301 and 302 andtlre winding of relay 303 to battery. Relays 319 and 303 operate. Relay 319 in operating closes a locking circuit for itself from battery through its winding and contact to ground at the upper contact of relay 301. Relay 319 also closes a locking circuit for relay 303 traceable through the contact of relay 319 to the ground at the upper contact of relay 301. These locking circuits for relays 31 9 and 303 are seen to be independent of the original circuits closed by the key 314. Hence, the key 314, if im mediately released, does not cause relays 319 and 303 to become deenergized. These relays will only release after the registration has been fully recorded on the register 310. Relay 303, in operating, closes a circuit from battery through its winding and left contact, thence over conductor 320, winding of relay 301, contact of relay 319, to ground at the upper contact of relay 301. Relay 301 does not energize at this time since its winding is shunted by the energizing circuit for rclay 303, above traced.

hen the key 314 is operated a circuit is also closed from ground through the left contacts of said key, conductor 321, conductor 322, winding of relay 323 to battery. Relay 323 operates and locks through its contact to ground at the upper contact of relay 301. As soon thereafter as relay 303 operates, a circuit is established from ground through the upper contact of relay 301, conductor 32 1, contact of relay 323, conductor 322, conductor 321, next to the innermost right contact of relay 303, winding of register relay 304 to battery. Relay 304 operates and closes a circuit from battery through the winding of relay 302, conductor 326, outermost left contact of relay 304, conductor 327, conductor 324, to ground at the upper contact of relay 301. Immediately that relay 302 operates it opens the shunt around the winding of relay 301 and this latter relay operates in series with relay 303. If the operator has not yet released the key 314 the operating circuit of relay 301 may be traced as follows battery, through the winding and left contact of relay 303, conductor 320, winding of relay 301, conductor 318, contactof key 314 to ground. If the operator has released the key, however, the operating circuit of relay 301 may be traced through the contact of relay 319, to ground at the upper back contact of relay 301. In either event the relay301 attracts its armatures and in so doing removes ground from conductor 324, whereby relays 303, 301, 319 and become deenergized as soon as key 314 is released, provided this key has not already been releascd by the operator. Relay 302 remains energized in a circuit from battery through its winding and inner up per contact, conductor 329, conductor 330, contact of relay 202, to ground at the contact of relay 203. Relay 304 also looks in a circuit from battery through its winding and inner left contact, thence over conductor 329, to ground at the contact of relay 203.

lVhen the operator depresses the next key 315, a circuit is closed from ground through the right contacts of said key, conductor 318, over a parallel circuit one branch of which extends through the winding of relay 319 and the other branch through the lower contact of relay 301, lower front contact of relay 302, conductor 332, lower back contact of relay 400, winding of relay 4.01 to battery. Relay 319 operates and closes a circuit from battery through the winding and left contact of relay 401, conductor 320, winding of i.'elay 301, contact of relay 319, to ground at the upper contact of relay 301. Belay 301, being shunted by the direct circuit from battery through the winding of relay 401 to ground, does not operate at this time. Another circuit is closed from ground through the left contact of key31 5, conductorlll, winding of relay 384 to battery. Relay334 operates and'loolts through its contact overconductor"i-l24,'to ground at the upper contact enemy "301.

When relay 401 operates, a circuit is closed from groundthrough the Contact of relay'32-l4, conductorlill-l, niiddle right contact of relay 401, winding of register relay 403 to battery. Relay 403 operates and looks through its inner left front contact, conductor 4%, conducttn 427, conductor 330, thence'to ground atthe contact of relay'208. Relay 403 also closes a circuit "from battery through the winding of relay 400, conductor 428, outer left contact of relay 403, conductor 429, conductor 824, to ground at the upper contact of relay 301. Relay 400 operates and locks throughits inner upper contact to the grounded conductor 426. Relay 400 opens the shunt around relay 301 and this relay energizes in series with relay 401. Relay 301 removes ground from conductor 2324, whereupon irelays'SlS), i 01, 334 and 401 become deenerg'ized, provided the key 315 has been re'leased'bythe operator.

When the operator depresses the next key 316,:a circuit is closed from ground through the rightcontacts of saidkey,-eonduc'tor 318, thence over a parallel circuit,;one branch of which leads through the winding of relay 319 and the other branch through the lower contact 01 relay 301, lower front contact of relay 3,02, conductor332, lower front contact of relay 400, lower loack contactot relay 408, winding 0t relay 409 to battery. Relay 409 operates and in a manner similar-to that already described completes a circuit rmitself in series with the winding of relay 301. Relay 301, howeve1-', being shunted does not operate at this time.-

The depression of key '316-a'lso establishes a circuit from: ground through the left contaetsot said key, co-nductor 335, winding of relay 336 to battery. Relay-386 operates and locks through grounded conductor 324. As soon as relay 409 operates a circuit is closed from ground over conductor- 324 through the contacts of relay 336, conductor 335, next'to the outermost right contact of relay 409, winding of register relay 413 to battery. Relay 4:13 operatesand locks through its inner le'it contact,conductor 431, to ground over conductor 427. Relay 413 closes a ei-runit from battery through the winding of relay 408, conductor 432 outer left contact of relay 413, conductor 433, conductor 324 to ground. Relay 4'08 loclts in a circuit from battery through its winding and inner up per contact, to ground over conductors 431 an d 4527. "Relay 408 at its lower back Contact opens the shunt around relay 301 and this relay operates to in turn cause the deener grization oi relays 330; 319, '301 and 409 in the manner above explained.

lower front contactso'li relays 40-0 and 40S,

lower contact of relay 41T, wnnling'ot relay 418 to battery. Relay 418 operates and closes a series circuit for itself and lthe Winding of relay 301 hutthe 1am]: relay does not operate for the reason explained. r 'rnother circ is trac'eahle 'froin 'ountl throughthe lower right contact o'it ey fi, conductor 321, conductor 322, winding of relay tobatteryi Relay leeks to the grounded conductor Still anothercircuit is closed from ground through the left controtsof key317, conductor 338, winding OtrelayBSQ to battery. Relay 33$) locks to the grounded conductor S24.

Assoon asrelay 418'operates, a circuit closed from the grounded conductor 2-324 through'the eontactso'f relay 334,1:ondnct0r 383,.n1iddle right contact of relay418, wind ing' of register relay 421'to-battery. Another circuit is closed "from the grounded conductor B24 throug"h the contact of relay 339,"eonductor 38, outermostright "contact of relay 418, wiruliug ofrelay 423 to battery. 'lelays 421 and L3 lockineircuitsthrough their inner 'let't contacts'to tl'ie-groilindedconductor 427.

Relay 421 closes a ci'rcu'it troni taut-1 hrou'gh the winding'of rlay417, conductor 435, outer left contact of relay 421,oonductor 324, to glGiUtCl atthe upper contact of relay 301 Relay 4 17'opens the shunt around the winding of relay 301 and this latter r lay becomes energized. Relay 30-1 opens the holding circuits-0t relays 323,339, 3 19,1301, 417 and418 and these relays all become deenergized. r i

At the time the switch 500 operates to extend the connecting ci'rcl'iiit 108 from the ojperatrifis position over the idle trunk 50.)

to the distant Inechanicalotlice, a circuit is closed for the relay This circuit leads from battery through the right-hand wi: l ing of said relay, lower left-hand Winding of repeating coll 006, contact 605 (1+2) of sequence switch 610'; ring conductor oi? the;

trunk through contacts otthe switch 500 to the ring conductor 130, inner left from Contact of. relay 1T9, inner upper back contact of relay 122, conductor 136, outer riht co n'tactot relay 200, right hand winding of relay "201 to ground. Another circuit is traceable from groundthrough the left-hand Winding of relay 003, upper left winding of repeating coil 000, contact '604 (1+2) ,tllGIlCG over the tip conductor thr'ougrh the contacts oi? switch 500 to tip conductor 1'29, 'outerlet't front contact of relay 119, uppermost back contact of relay 122, conductor 185, inner right contact of relay 200, left-hand winding of relay 201 to battery. Relay 20=1 operates in this circuit and closes a circuit from battery through the winding of relay 204, front contact of relay 201, contact of relay 202 to ground through the contact of relay 208. Relay 20% operates and locks through its right contact to ground at the contact of relay 20 3.

Relay 603 also operates in the circuit traced and completes a circuit from ground through its contact, contact 611 (1), wind-- ing of sequence switch magnet 610 to battery. Sequence switch 610 is energized in this circuit and moves out of position 1 and into position 2. As the sequence switch 610 passes through position 1% it closes at its contact 609 a temporary circuit for the slowto-release relay 608. Relay 608 operates and remains operated provided the sender selector switch 602 has its brushes on the ter minals of a busy sender at this time. The holding circuit for relay 608 may be traced from battery through its winding, contact 652 (2), conductor 634, brush 616 and the terminal on which it isstanding, thence through the multipled terminal of some other sender selector switch and through the corresponding brush 616 thereof, to ground at the contact 607 of the particular sequence switch 610 associated with said other sender selector switch. The contact 607 of the sequence switch associated with the sender selector which is rendering the register sender busy will be in some position between positions 4 and 18. Relay 635 is also energized in parallel with relay 608 over conductor 6341, brush 616 to the grounded busy test terminal. lVith sequence switch 610 in position 2 and relay 635 energized, a circuit is completed from battery through the winding and contact of the sender selector stepping magnet 61% through the contact 613 closed in position 2, to ground at the contact of relay 685. Magnet 61 1 interrupts its circuit and advances brushes 615 to 618, inclusive, from position to position to search for an idle register sender. Assuming the sender shown in the drawing is idle at this time, no ground potential exists on the terminal encountered by brush 616 and consequently the circuit of relays 635 and 608 is opened. Relay 635 releases immediately and opensthe circuit of stepping magnet 614. to prevent further advance of the switch 602. After an interval relay 608 releases and a circuit is closed from ground through the contact of said relay, contact 612 closed in positions 2 and 8, winding of sequence switch magnet 610 to battery. Sequence switch 610 advances its contacts from position 2 through position 8 and into position l. With sequence switch 610 in position 4,

ground potential is applied by way of contact 607 to the multipled terminals with which the brushes 616 of all sender selector switches cooperateto identify this particular sender as busy.

hen sequence switch 610 passes out of position 2, it opens at contacts 604 and 605 the circuit previously traced for relay 201 in the manual otiice. -Relay 201 releases and a circuit is completed from battery through the winding of the sta rt relay 200, outer left contact of relay 204, back contact of relay 201, contact of relay 202 to ground at the contact of relay 203. Relay 200 operates and'locks through its inner left contact to ground at the contact of relay 208. Vith 'relay 200 operated, a circuit is closed for relay 207 as follows, provided relay 802 has been energized: battery, through the winding of relay 207, conductor 220, lowermost contact of relay 309, uppermost contact of relay 302, conductor 340, to ground at the inner left contact of relay 204.

The apparatus is now in condition for transmitting code impulses over the line circuit in the distant mechanical office for setting the register sender shown in Figs. 6 and 7. -The code impulses are sent to the indicator mechanism over a full metallic circuit comprising both the tip and ring sides of the line in series. These impulses may be of either positive or negative polarity dependent upon the pole of battery that is connected to a given side of the line circuit. They may also be weak or strong dependent upon whether high or low resistance is included in the circuit. Relay 620 at the distant end of the impulse circuit is polarized in such a manner as to respond only when current of positive polarity flows over the ring side of the line that is, over the conductor 636. The relay 621 is polarized in such a manner as to respond to current of the opposite polarity. Both relays 620 and 621 respond either to strong or weak impulses provided the polarity is in the proper direction. The relay 619 responds to strong impulses of either polarity but does not respond to weak impulses.

Relays 208 and 209 at the manual oilice cooperate with each other to measure intervals or time during which code impulses are produced and propagated over the line circuit to the distant oflice. Due to the characteristics of these relays they operate and release slowly. Relays 211, 212, 213 and 2141 operate in a definite sequence and their function is to measure a sufficient number of periods or code impulses to represent each of the different digits;

Relay 207, in operating, establishes a circuit from ground through the inner left contact of relay 20-1, outermost left contact of relay 207, inner right contact of relay 218, inner right contact of relay 211, outer right contact o't relay 212, left back contact of relay 213, left-hand Winding 'ot'relay 214, left hand winding of relay 213 to battery. Relay 213 being marginal doe-snot operate in this circuit. Relay 214, however, operates and a circuit is closed from bz'ittery through the lett-hand winding; of relay 213, left- -hand Windingot relay 214: right-hand \Vi1](l ing of relay 21?), inner rig-ht contact of relay 214-, to the grounded conductor 340. Relay 213, however, does not operate since its righthand winding is shunted by the circuit pie viously traced. Relay 214- closcs a circuit from ground through its out-er right contact, conductor 221, contact of relay 311, innern'iost upper back contact otrclay 300 wind ing oil relay 308110 battery. Relay 308 operates and ch .es a circuit from battery through its Winding andcontact', Winding of relay 311, thence to ground over conductor 221i Relay 311, however, does not operate since its winding is shunted by the circuit origii'ially traced tor relay 308. Relay 308 at its right-hand arinatures connects the thousands register 310 to the lll'lpulse circuit in Fig. 2 for determining the transmission oi the thousands digit.

Relay 207 also closes'a circuit from battery through the resistance 215, Winding of relay 208,1ctt back contact ot'relay 200, conductor 222, conductor 2L3, innermost lettcontact of relay 207 to ground at the outer let't contact ot relay 200. Relay 208 energizes after an interval and closes acircuit from battery tl'irough the resistance 216, winding o't relay 200, inner left contact of relay 208, tothe grounded conductor 222. Relay 200' operates after an interval and closes a circuit from battery through the Winding of relay 210, inner'lett normalcontact of said relay, outermost right'front contact of relay209 to ground over conductor Relay 210 operates and locks through its innermost left armature to the grounded conductor 223. Immediately that relay 200 operates, it closes acircuit from battery through the resistance 215, middle right contact of relay 205), to ground over conduct-on222. This circuit shunts the relay 2 8 which releases after an interval.

' l' i hen relay 208 becomes released it closes a circuittroin battery through the resistance 210, right back contact of relay 208 to around over conductor 222. This circuit shunts the relay 200 which releases its arnia tures after an interval. l hile relays 208 and 209 are releasing an impulse is transmitted over the line to the distant mechanical otlice. The circuit for this impulse may he traceditroin grouinlovcrthe positive pole ot' battery. throiurh the outer right contact of relay 210, middle lettcontact of relay 20?, conductor225, thence through the normal contact at the middle right-hand arn1a- 'ture of relay 205, condiiictor'l36 and thenc over the ring side ot the line as previously traced through the sequenceswitch con tact 605'closed'in position4, conductor 630,

brush 618, windings 0t relays620, 621 and 019 in series,- brush 611T, conductor'tlST, contact 004 and thence returning" over the tip side of the line'to conductor 135, inner normal contact of relay 205, conductor 226, left back contact 0t relay 212, conduct-or outer right contact otrelay- 207, con1 ductor 228, uppermost back contactofrelay Zl00,-ri g;ht contact of relay 304i, conductor high resistance Sl2 tothenegativepole itiery. Bile to the high resistance312, the impulse is weak in character. Consequently, the marginalrelay 019 does not re spond. Due to the-polarity ot the impulse circuit, the polarized relay 20 responds. Relay 620 operates and closes a circuitfroi'l'i ground through the contact of relay 639, coi'itact-ot relay 620, left back. contact of relay (S23, lett back contactoit-relay 6%, con ductor 040, left-hand Winding ot register relay 708 to battery.

It will be noted that the relay (it-l0 isoperated as soon as sequence switch 610 moves into position latter the idle register sender has been seized. The operating circuit of this relay is traceable from battery tl-irough erates and opens the impulse circuit to in terrupt the impulse being transmittedover the line. Re1ay205 looks through its lett contact to ground over conductor WV hen the impulse circuit is interrupted, relay 020 at the mechanical" oiiice becomes deenergized.

l-lelay 209 in releasing also completes a circuit from ground over conductor 222, through the outer right back contact of relay 209 outermost let't contact ol'rclay 0, conduct or 220, left back contact of relay 211.

left hand wiiidin of rela i 212 hilt-hand a 1 \i 'inding ot'relay 211 to battery. Relay 2l2 operates in this circuit, but relay 2L1 being): marginal does not receive: sufficient current to attract its arinatures. Relay 212 com- ,1-'5 1 i i 1' m b: it y 1 VP U] .51 plots .1 circuit -lOill awry chea o inc left-hand windings 0t relays 211. and in series through the right-h and winding oi relay 21.1, inner right contact of relay 212 to the grounded battery 3 1-0. Relay 211, however, does not operate in l'lllS circuit since its-Winding, brush 010, conductor conits right-hand winding is shunted due to the ground potential on conductor 229. Relay 212 at its outer right contact opens the shunt around the right-hand winding of relay 213 and this relay operates in series with relay 214.

When relay 213 operates, a circuit is closed "from ground through the contact ot relay 203, contact of relay 202, conductor 230, outor right contact of relay 213, conductor 231, inner right-hand contact of relay 303, wind ing of relay 309 to battery. *telay 309 operates and looks through its inner lower contact to the grounded conductor 330. Relay 309 opens the shunt around the winding of relay 311 and this latter relay operates in series with relay 308 in the circuit previously traced.

The next period for the transmission of an impulse is determined by the interval required for the relays 208 and 209 to reoperatc. Immediately that relay 209 releases, the energizing circuit previously traced is closed "for relay 20S and this relay operates ai'ter an interval. As soon as relay 208 operates it closes the circuit for relay 209 and this relay also becomes energized. During the interval required for the operation of relays 208 and 209, an impulse circuit is closed from the positive pole of battery through the outer right contact of relay 210, middle leil't contact of relay 207, conductor 225, innermost right front contact of relay 205, thence over the tip side of the line to the windings o'l' relays (319, 620 and 621 and returning over the ring side of the line through the middle right front contact of relay 205, conductor 232, high resistance 312 to the negative pole of battery. Due to the character of this impulse only the relay 621 is operated. Relay 621 completes a circuit from ground over conductor T06, contact of relay 621, conductor Gil, left back contact of relay 622, left-hand windings of relays 623 and 622 in series to battery. Relay 622 being marginal does not operate, but relay 023 attracts its armatures. Relay closes a circuit from battery through the left-hand windings of relays (322 and 623 through the right-hand winding of relay 622, inner right contact of relay 623 to the grounded conductor 706. Relay (322, however, remains dtwnergiaed since its right-hand winding is shunted due to the presence of ground on conductor 0-1-1. Relay 02-3 closes a circuit from ground on conductor 706, through. the outer right-hand contact of relay 022, left back r.ontactof relay 625, winding of relay (32% to battery. Relay 62%: operates and closes a circuit from battery through its winding and the winding of relay 025, inner right contact of relay 621, conductor (H2, conductor 706 to ground. Relay (324: operates but relay 025 being shunted. remains inert.

When relay 209 operates, it removes ground from conductor 229 whereupon relay 211 operates in series with relay 212 in the a circuit previously described. Also, when rclay 209 operates it closes a circuit from battery through resistance 206, conductor 23%, middle let't contact of relay 210. outermost right front contact of relay 209 to the grounded conductor 222. This shunts the relay 205 which releases its armatures and interrupts the impulse being transmitted over the line.

Relay 621 on releasing removes ground potential from the conductor (fll'whereupon the relay (322 operates in series with relay 623.

The next period for the transmission of an impulse is measured by the deenergization of relays 208 and 209 which takes place in the manner previously described. During the interval that these relays are undergoing release, a path is traceable from positive battery over conductor 225, thence through the middle normal contact of relay 205, over the ring side ofthe lin and returning over the tip side through the normal contacts oi relay 205, conductor 226, left front contact of relay 212, conductor 23 1, through the next to the outer contact of relay 308 to the armature of relay 306. Since relay 300 is not operated, the impulse circuit is held open at this point and no impulse is transmitted over the line during this period. lVhen relay 209 lina-lly releases, it closes a circuit from ground over conductor 222, outermost right contact of relay 209, outermost lei't contact of relay 210, conductor 229, left front cont act of relay 211, left-hand winding of relay 211 to battery. Relay 211 remains energized in this circuit, but relay 212 being shunted releases its armatures. telay 209 also opens the shunt around relay 205 and this latterrelay operates to prepare the line circuit for the next impulse period.

Relays 208 and 209 now become energized succession and during the interval required for their energization an impulse is transmitted over the line. A circuit for this impulse leads from the positive pole of battery over conductor 225, thence as previously traced over the tip side of the line and returning over the ring side of the line through the middle front contact of relay 205, conductor 232, high resistance 312 to battery. Due to the character of this impulse only the relay 621 is operated. Relay 621 applies ground potential to conductor 6%1 whereby relay 622 is held energized but relay 623 being shunted releases its arma tures. Upon the release of relay 623 the shunt around the winding of relay 625 is maintained through the inner right contact of relay 622. lVhen relay 209 finally ener gizes it opens the holding circuit for relay 211 and this relay releases. A circuit is now circuit closed trom batter through theleft-hand winding and left front contact of relay 213, outer right contact of relay 212, inner rlght contact of relay 211, inner right itrontcontact of relay 213. inner right front contact of relay to the grounded conductor 340. Relay 219% is shunted by this circuit and releases its armatures. Relay 21 1- on releasing opens the holding circuit of relay 213 and said latter relay also deener e izcs. Relay 209 in operating also closes the shunt around the winding of relay 205 and this latter relay retracts its armatures to interrupt the impulse being transmitted to the line. I

Then the impulse is interrupted relay 621 releases and opens the holding circuit of relay 622 Relay 622 releases and removing the shunt around relay 625 permits this latter relay to operate in series with relay 625.

Relay 211 in releasing removes ground from conductor 221 whereupon relays 311v and 303 become deenergized. Relay 303 disassociates the register 310 from the impulse circuit of Fig. 2.

lVith relays 211, 212, 213 and 214 released, the circuit originally traced is completed tor the left-hand windings of relays 213 and 214. Relay 214 operates but relay 213 remains deenergized, being shunted. Relay 21 1- completes a circuit from ground through its outer right contact, conductor 221, contact o't relay 311, innermost upper frontcontact ot relay 309, innermost upper bacl: contact of relay 4-06, winding of relay 107 to battery. Relay 407 operates and closes a circuit from battery through its winding and left contact, conductor 438, wiiulini'g of relay 311, thence to ground over conductor 221. Relay 311, however, remains shunted until relay 106 is operated. Relay 1-07 associates the hundreds register 110 with the impulse circuit.

During the next period relays 208 and 209 undergo deenergization but since relay 102 of the hundreds register is deenergized no impulse is transmitted over the line. When relay 209 releases relay 212 becomes operated. relay 213 operates in series with relay 21%1- and relay 2-05 energizes in the manner already fully explained. Relay 213 closes a, circuit from ground on conductor 230 through its outerrigrht contact, conductor 231, innermost right contact of relay 607, winding of relay 106 to battery. Relay 4:06 operates and locks to ground over conductors 427. and 330. Relay 406 opens the shunt around relay 311, which operates in series with relay 4107 in the circuit traced.

During the next period relays208 and 209 undergo energization and an impuls oilice. The circuit for this impulse leads from the positive pole of battery over conlay 205, oyer the tip side of the line and retiu'nin g over the ring side of the'jline to the middle rip ht contact of relay 2 05, outer right contact of relay 205, conductor 235, outer right back contact. of relay 211, conductor 236, next to the inner right contact 01'' relay 407, left contact of relay 403, conductor 139, low resistance 313 to battery, Due to the char cter of this impulse both relays 619 and 621 are operated. Relay 621 closes a circuit 'hereinbefore traced for relays 622 and 623 and relay 623 operates, relay 622 remaining inert. Another circuit is closed from ground at the contact of relay 639, through. the contact of relay 619, outer right back contact of relay 622, inner right front contact of relay 625, inner right back contact of relay 627, conductor 643, lefthand winding of relay 709 to battery. Relay 709 operates and locks to the grounded conductor 1. Relay 623 in energizing completes a circuit from ground over con ductor 706, outer right contact of relay 623.

left front contact of re1ay left bile-kit contact of relay 627, winding of relay 626 to battery. Relay 626 operates and closes a circuit through its winding and the winding of relay 627, through the inner right contact of relay 626 to the grounded conductor 64-2. Relay 627 being shunted, however, does not operate.

When relay 209 becomes energized at the end ofthe period ground removed from conductor229 and relay 211 operates explained. Also, relay 205 is shunt-d and'releases. Relay 205 opens the impulse circuit whereupon relays 619 and 621 becon ie deenergized. Relay 621 removes ground from conductor 6:11 and relay 622 operates in series With relay 623.

Relays 203 and 2 9 become deenergized next, but during the interval required for their release no impulse is transmitted over the line. l i hen rrlag. 209 finally releases, relay 212 becomes decnergized and relay 205 operates as already described.

The next and last interval is measured by the energization oi? relays 203 and 209. During this time an inipulseXcircuit is closed from positive battery over conductor 225,

through the inner right front contact of relay 205, over the tip side of the line returning over the ring side of the line, through le right front. contact of relay 205,

the mido. r conductor 232, throupjh the high resistance to conductor 6 11 and relay 623 is shunted,

out. is transmitted over the line to the distant hen relay 209 becomes energized, relays 211, 213, 2 14i and 21.) are all deenergized in the manner hereinbetore explained. Relay 205 opens the impulse circuit and relay 621 becomes deenergized to open the circuit of relay 622. Relay 622 removes the shunt from around the Winding of relay 627 and this relay operates in series with relay 626. Relay 214, on releasing, opens the holding circuit of relay 407 and relay 311. Relay 407 disconnects the hundreds register 410. Relay 214 is immediately operated again in the manner explained, While relay 213 being shunted remains deenergized. Relay 214 in operating connects ground potential to conductor 221 and a circuit is extended thereover through the contact of relay 311, inner upper front contacts of relays 309 and 406, inner upper back contact of relay 416, Winding of relay 415 to battery. Relay 415 operates. and closes a circuit through its winding and contact, conductor 438, through the Winding of relay 311 to ground on conductor 221. Relay 415 operates and associates the tens register 420, but relay 311 remains inert.

Relays 208 and 209 undergo deenergization at Which time relays 212, 213 and 205 are operated. Relay 213 in energizing closes a circuit from ground over conductor 230, through the outer right contact of relay 213, conductor 231, innermost left contact of relay 415, winding of relay 16 to battery. Relay 416 operates and locks to the ground ed conductor 427. Relay 416 opens the shunt around the Winding of relay 311 and this latter relay operates in series With relay ill 211 operates and relay 205 releases.

Next the relays 208 and 209 become energized and during the period of their energization, a circuit is closed from ground over conductor 225, through the inner right vcontact of relay 205, over the tip side of the line, returning over the ring side of the line, through the middle contact of relay 205, conductor 232, through the high resistance 312 to battery. Due to the character of this impulse only the relay 621 is operated. Relay 621 in the manner already explained causes the energization of relay 623. Relay 623 completes a circuit from the grounded conductor 706. through the upper right contact of relay 623, the left front contacts of. relays 625 and 627, left back contact of relay 629,

Winding of relay 628 to battery. Relay 628 operates and closes a series circuit for itself and relay 629, but relay 629 remains shunted.

When relay 209 becomes energized, relay Relay 205 opens the impulse circuit and causes the release of relay 621. Relay 621 causes the energization of relay 622.,

Relays 208 and 209 become deenergized during which time an impulse circuit is closed from positive pole of battery. over conductor 225. thence over the ring side of the line and returning over the tipside of the line by Way of conductor 226, left front contact of relay 212, conductor 234, next to the outer right contact of relay 415, outer right contact of relay 413, conductor 342, re-

relay 620, left front contact of relay 623,

outer right front contacts of relays 624,626 and 628, left back contact of relay 630, conductor 645, left-hand Winding of relay 710 to battery. llelay 710 operates and locks to thegrounded conductor 7 06.

l Vhen relay 209 becomes released it causes thedeenergization of relay 212 and the op eration of relay 205. Relay 205 opens the impulse circuit and relay 620 releases. Next the relays 208 and 209 become energized and during this period an impulse circuit is closed from positive battery over con ductor 225, thence over the tip side of the line and returning over the ring side of the line, through conductor 232, resistance 312 to the opposite pole of battery. Due to the character of this impulse, only the relay 621 responds. Relay 621 in the manner explained causes the release of relay 623. When relay 209 finally operates relays 211, 214, 213 and 205 become deenergized. Relay 205 opens the impulse circuit and relay 621 releases. Relay 621 opens the holding circuit of relay 622, whereupon relay 629 operates in series With relay628 as already explained. Relay 214, in releasing, opens the holding circuit of relays 311 and 415. Immediately thereafter relay 214 is again operated in a circuit including the left-hand Winding of relay 213, but relay 213 remains deenergized as above explained. Relay 214 closes a circuit from ground over conductor 221, contact of relay 311, thence through contacts of relays 309, 406v and-416 and through the lowermost back contact of relay 424, Winding of relay 425 to battery. Relay 425 operates, closes a circuit through its Winding and contact and the Winding of relay 311 to ground over conductor 221. Relay 311 being shunted does not operate at this time.

Relays 208 and 209 next become deenergized and during this interval an impulse circuit is closed from positive pole of battery over conductor 225. thence over the ring side of the line, returning over the tip side of the line. through conductor 226, left back contact of relay 212, conductor 227, outer right contact of relay 207. conductor 228, uppermost front contacts of relays 309, 406

and 416, upper back contact of relay 424..

right contact of relay 419,conductor 342. high resistance 312 to battery. Due to this impulse relay 620 is operated. Relay 620 closes a circuit from ground, through its contact, left back contact of relay 623. left front contacts of relays 624, 626 and 628,

conductor 646, left-hand Winding of relay 711 to battery. I Relay/711 operates andlocks through its 'vindings to the grounded eonductor 706.

When relay 209 releases, relays 212 213 and 205 are energized. W hen relay 213 operates, it closes a circuit l roni ground over conductor 250, through its outer right contact, thence over conductor 231, through. the innermost right contact of relay 125, Winding: of relay 1-2 1; to battery. Relay 4-24- operates and loclrs to the grounded conductor 4-21. Relay 41-2-1 opens the shunts around the. winding of relay 311 and this relay operates in series with relay 4-25. Belay .205 interrupts the impulses and causes the release of relay i320.

Next the relays 208 and 209 undergo energization during which time an impulseis transmitted from the positivepole of battery, over conductor 225, thence over the tip of the line and returning; over the ring side of the line, through conductor 232 and resistance 31.2 to battery. )ue to this impulse the relay 621 alone operates and in so doing closes a circuit for. the operation of relay 623. Relay 623 closes a circuit from ground, over conductor 706, through the outer right contactof relay 023, thence through the left front contacts of relays 627 and left back contact of relay 631, winding of relay 630 to battery. Belay 630 operates and. closes acircuit for itself and relay 631, but this latter relay being shunted does not operate. ll hen relay 209 becomes energized it causes the energization of relay 211 and the release of relay 205. Relay 205 opens the impulse circuit and causes. the oeenergization of relay 621, whereupon relay 622 operates.

Relays 208 and 209 next become deenergized andas soon as this happens relay 212 releases and relay 205 operates. hi -ext relays 208 nud209 operate and during; the interval. of their euergizatioii an impulse circuit is closed from positive pole of battery, yer conductor 225, thence over the tip side of the line and returning over the ring; side of the line, through the middle right front contact of relay 205 outer right contact of relay 125 conductor outer right front Contact of relay 211, conductor 238, outermost rig-ht contact of relay right contact of relay .23 conductor ass). low resistance 313 to the opposite pole of battery. Due to the low resistance 313. relay 619 operates in addition to relay 021. Relay 021 causes the release of re-. lay 623 in the manner described and relay 619 closes the circuit from ground through its contact outer right front Contact of relay 62.2, outer right front contacts of relays 625, 627 and 629, conductor 64 :8, right-hand winding of relay 712 to battery. Relay 712 operates locks to the grounded conductor 706. ll lien relay 209 finally becomes energized it causes the release of relays211, 214, 213 and 205.

relays become deenergized.

Relay 205 in releasing opens the impulse circuit and relays 619 and 621 become .deenergized. Relay 621 opens the holding circuit of relay 622 and this relay releases to re-. more the shunt from around the winding of relay 631. Relay 631 thereupon operates in series with relay 630 and locks to the grounded conductor A erators position will now be described. As soon as relay 214-. releases, it opens the hold ing circuit of relays 311 and 125 and these Immediately thereafter the relay 21 1 operates in the man nor previously described. Relay 21 1; now closes a circuit from ground through its outer right contact, conductor 221, contact of relay 311, innermost upper front contar 'oif relays 309, 406 and 416, lowermost front contact of relay e24, conductor 4 10, w nding of release relay 203 to battery. Relay 203 operates and removes ground from coiiductor 230 whereupon all energized relays are immediately released and the sender is restored to its normal. condition.

Relay 203 in iiperating also opens the bolting circuit of" relay 119.. Relay 119 roleases, disconnecting the sender from the connecting circuit 108 and completing said circuit 108 for conversation.

With the record of the called line number established on the numerical registers in Fig. 7, the sender may exercise control over theselectire switches 000 and 001 illustrated diagrammatically to extend the incoming trunk through to the called subscrihers lineellthough the register sender is not fully shown in all its details it will be understood that the registers 700, 701 and 703 after taking their settings correspondine to the digits of the numbers may determine the operation in any well-known manner o'l."

a set of counting relays or other similar dc.-v vice for measuring the amount of move-- .ment taken by the selecto switches 600 and 2601.

iereii-t digits from 0 to 9 shown in connew' The small circles including the dittion with the registers indicate POiIiilSl from which multiple taps he made in the usual manner to the counting relay set,

After a sender has rece ved its record and is ready to exercise control. over the first selective switch 600. a condition is brought about as by the advance of a sequenc o controlling switch. (not shown) whereupon a contact 656 is cloe d toestablish a 'icr t through brush 61.5, contact 650, n'ii'idi" of sequence switch 610 tobatt y. Seerence switch 610 moves: out oi. posit-1on4 and into some position beyond where the first selective movement of the switch 600 is made. For a more complete description of a reg-1 release of the register sender at the op-' ister sender of t-he same general type of the one illustrated in Figs. 6 and 7 wherein registers of the relay type determine the opera.

tion of counting relays to in turn determine the selective movement of switches, refer ence is made to the patent to Lundell and Stearn, 1,345,016 granted June 29, 1920.

After the conversation has been completed, the subscribers replace their receivers on the switchhooks and the operator at the position shown in Fig. 1 receives the usual diconnect signals. She removes the plugs 104 and 106 from the respective jacks whereupon relays 107 and 121 become deencrgized. Relay 121 opens the holding circuit of relay 120 and also the holding circuit of the horizontal magnet 512 and relays 523 and 522. Magnet 512 restores the associated rod and the connection through the switch 500 is released. The release of the switch 500 and the disconnection from the outgoing trunk 509 may bring about the release of switches 600 and 601 in any well known manner.

It will be assumed next that the operator at position 105 receives a call for the distant mechanical ofiice illustrated at a time when all of the connecting circuits 10S and 109 at her position representing this oftice are busy. The operator on finding that the circuit 115 at the adjacent operators position 110, which represents the same called oflice, is idle, she may appropriate this circuit for use by inserting the overflow plug 118 in the overflow jack 117 of said circuit 115. The insertion of the plug 118 in jack 117 closes a circuit from battery through the winding of relay 128, through the sleeve of the jack and plug, thence over conductor 137, winding of relay 202, contact of relay 203 to ground. Relay 128 operates and disconnects the con'ductors 1&0, 141 and 1.42 which lead to the sender associated with the adjacent operators position. 110. In this manner. the circuit 115 is rendered nonconnectihle to the adjacent operators sender, and is connected instead through the overflow plug and jack to the conductors 135, 136 and 137 leading to the sender at the position 105. Next the operator at posi tion 105 inserts the plug 106 of her regular cord circuit in the regular jack 116 of the connecting circuit 115 which she has appropriated-toruse. The insertion of plug 106 in jack 116 causes the operation of the switch 500 or another switch similar thereto in exactly the same manner as described in connection with the first call. The operator now sets up a number on her keyboard and thereafter the register sender transmits code impulses to record the record of an idle sender in the distant mechanical office. After the connection has been completed and conversation is over the equipment is released by the operator removing the plugs of her cord circuit from the respective j acks.

tive switches are employed for further extending the connection, it will be understood that the record may be received on an indicating mechanism and the number corresponding displayed before an operator and the operator may complete the Connec tion manually.

sender comprising a plurality of registers for storing designations, means responsive to the act of the operator in making connection with one of said circuits for connecting the register sender to such circuit, and means controlled by the sender for governing the operation of said selective switch.

2. The combination with an operators position of a number of conversational circuits terminating in jacks at the operators position, plug-ended cord circuits at said position, a group of trunks, a switch responsive to the insertion of a plug in the jack of one of said conversational circuits for connecting said circuit to one of said trunks, a

selective switch for further extending said trunk, a register sender for storing designations at the operators-position, means responsive to the insertion of the plug in the jack of said connecting circuit for connecting the register sender to such circuit, and means controlled by the sender for governing the operation of said selective switch.

3. The combination with an operators position of a plurality of connecting circuits outgoing therefrom, a group of trunks, and a cross-bar. switch responsive to the act of the operator in making connection to any one of said connecting circuits for connecting such circuit to one of said trunks.

4c. The combination with an operators position of a plurality of conversational circuits terminating in jacks thereat, plugended cord circuits at the operators position, a group of trunks, and a cross-bar switch having links, said switch being responsive to the insertion of any number of said plugs in the jacks of different conversational circuits for establishing co-existing connections between such conversational circuits and said. trunks.

5. The combination with a plurality of operators positions of conversational circuits outgoing from each position, a group of trunks, a sender at each position, means when the operator at any position makes .1

connection With one of the conversational 

